Operating mechanism of the organic metal-semiconductor field-effect transistor (OMESFET)

Organic metal-semiconductor field-effect transistors (OMESFETs) were fabricated with a polycrystalline organic semiconductor (pentacene) and characterized in order to systematically analyze their operation mechanism. Impedance measurements confirmed full depletion of the thick pentacene film (1 m) due to the low doping concentration of unintentional doping (typically less than 10 cm). The necessity of developing a specific device model for OMESFET is emphasized as the classical (inorganic) MESFET theory based on the depletion modulation is not applicable to a fully-depleted organic semiconductor. By means of joint electrical measurements and numerical simulation, it is pointed out that the gate voltage controls the bulk-distribution of injected carriers, so that the competition between the gate and drain currents is critical for determining the operation mode. Finally, the geometrical effect is investigated with comparing a number of transistors with various channel widths and lengths. PACS numbers: 81.05.Fb; 85.30.Tv; 72.20.-i; 85.30.Kk a E-mail: [email protected] Phone: +33 1 69 33 43 21, Fax: +33 1 69 33 43 33 Manuscript for Eur. Phys. J. Appl. Phys. Special Issue DIELOR 2010